Gas turbine engine oil systems require a separator for separating air and oil from the air/oil mixture produced during engine operation. These mixtures vary from oil emulsified with air, to air contaminated by droplets of oil. For example, the compressed air streams used in gas turbine engines to pressurize labyrinth seals for the engine main bearings in order to avoid excessive loss of lubricating oil, invariably become contaminated with oil in the form of particles suspended in the air. Loss of contaminated air from the labyrinth seals in the compressor disadvantageously causes fouling of the engine parts and produces noxious and unpleasant contaminates in air drawn from the compressor for cabin pressurization. Engine oil tanks, auxiliary gearboxes, and the oil system in general contain a pressure above the ambient pressure and need to vent to the atmosphere. The increased loss of lubricating oil from the engine oil tank further disadvantageously necessitates larger capacity oil tanks, thereby adding to the overall weight of the engine, which is particularly a problem relating to aircraft engines. Centrifugal separators have been extensively used in the aircraft industry in attempts to remove the majority of oil mixture from compressed air streams. However, efforts have been continuously made in the aircraft industry to improve the efficiency of air/oil separators in gas turbine engine oil systems.
Additionally, industry trends are moving away from mechanically/gearbox driven, to electrically driven accessories, so the availability of an appropriate shaft/drive to operate a conventional centrifugal separator will be reduced or possibly eliminated in the future.
Accordingly, there is a need to provide an improved air/oil separator for use in gas turbine engines.